VAIO Drivers Install Problem

Salute everyone!

I have been trying to fix my friend's Sony Desktop VAIO PCV-RX755 P4 2GHz/512/80/DVDRW, on
which a technician, from a local PC Shop, gave up.

PC would not boot, with a message displayed "NTLDR not found,
Ctr+Alt+Del to restart".

I replaced the original HDD with IBM's and successfully loaded Windows
XP Pro. However, none of the VIDEO, AUDIO, or Ethernet works.

In device manager:
- there is no Display Adaptor Icon, or monitor icon even Present,
- Audio driver - present and shows "This device is working properly"
- there are two yellow question marks listed as unknown devices.

All Audio , Video and Ethernet are on board integrated.

I have updated BIOS, installed Sony System Shared Folder, Video driver,
Audio Driver, Ethernet Driver - all in accordance with Sony's website
instructions.

Technician at Sony was not very helpful and only recommended to take
PC to a Service Center.

COULD SOMEONE TELL ME WHAT'S GOING ON WHITH THIS MACHINE, AND ADVISE ON HOW
TO FIX THOSE DRIVERS, besides replacing SONY's MB and HDD, followed by A
Quick restore. Is there a "special way" to do it for SONY's PCs?

Thanks to everyone in advance.

Igor K>